Circular Doubly Linked List: Insert at Front
#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *llink;
struct node *rlink;
};
typedef struct node* NODE;
NODE getnode();
NODE insert_at_front(NODE last,
int item);
void display(NODE last);
NODE getnode()
{
NODE x;
x =(NODE) malloc(sizeof(struct node));
return x;
}
NODE insert_at_front(NODE last,
int item)
{
NODE temp;
temp = getnode();
temp->data = item;
if(last == NULL) /*Case 1: List is empty*/
{
last = temp;
}
else /*Case 2: If not empty*/
{
temp->rlink = last->rlink;
last->rlink->llink = temp;
}
temp->llink = last;
last->rlink = temp;
return last;
}
void display(NODE last)
{
NODE
cur;
printf("\nContents are:\n");
if(last == NULL)
printf("\nList is empty. Nothing to
display.");
else
{
cur = last->rlink;
while(cur != last)
{
printf("|%d
| %d | %d | ==> ",
cur->llink, cur->data, cur->rlink);
cur =
cur->rlink;
}
printf("| %d | %d | %d
| ", cur->llink, cur->data,
cur->rlink);
}
}
void main()
{
int ch, item;
NODE last = NULL;
while(1)
{
printf("\n\n~~MENU~~");
printf("\n1.Insert
at front");
printf("\n2.Display");
printf("\n3.exit");
printf("\nEnter your choice: ");
scanf("%d",&ch);
switch(ch)
{
case 1: printf("\nEnter the value:
");
scanf("%d",
&item);
last = insert_at_front(last, item);
break;
case 2: display(last);
break;
case 3: exit(0);
}
}
}
Output:
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 1
Enter the value: 11
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 2
Contents are:
| 70920 | 11 | 70920 |
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 1
Enter the value: 12
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 2
Contents are:
|70920 | 12 | 70920 | ==> | 70944 | 11 | 70944 |
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 1
Enter the value: 13
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 2
Contents are:
|70920 | 13 | 70944 |
==> |70968 | 12 | 70920 | ==> | 70944 | 11 | 70968 |
~~MENU~~
1.Insert at front
2.Display
3.exit
Enter your choice: 3
